Lifecycle Analysis: It’s Worth the Effort

Performing a risk analysis as part of an IEC61508/61511/ISA 84.01 safety lifecycle process can be quite challenging. How can you be sure you get what you need within budget and how can your team provide the best value for money? When these services are brought in from outside, it can be difficult to see high quality and the value of that quality in advance. But it is almost always easy to see the cost. Also the buying decision is often based on the project requirements rather than the overall life of the plant requirements. As a result, this situation can easily lead to a lower quality risk analysis. This problem is what classical economics calls “the market for lemons,” and…

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Babies, Bathwater, and Australian Safety Laws

The old saying goes, “Don’t throw the baby out with the bathwater.” But it looks like a number of people in Australia may be in danger of doing just that with their response to the country’s newly harmonized health and safety laws.

Australia’s new Work Health and Safety Act says company officers “… must exercise due diligence to ensure that the person conducting the business or undertaking complies with that duty or obligation.” An organization also must ensure “workers and other persons should be given the highest level of protection against harm to their health, safety and welfare from hazards and risks arising from work … as is reasonably practical.”

So far, the…

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The Safety Lifecycle as a Risk Control Loop

I have been doing a number of recent projects introducing the safety lifecycle to companies that are new to the field. As a result I have been playing with various ways to think about the overall safety lifecycle philosophy. As many of the more experienced readers are aware, the overall safety lifecycle ideas are not new. But, it is worth looking at these ideas in a variety of ways to ensure we are implementing them as effectively and clearly as possible.

Today’s blog supports this goal. It presents the safety lifecycle as a basic feedback and control loop to achieve a set point value for risk as shown in the figure.

In this risk management…

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Replace Before Failure

The solenoid valve manufacturer provides an FMEDA report that lists “useful life = 12 years.”  Useful life is a reliability engineering term that indicates a point in time when the failure rate of a device will begin increasing rather rapidly.  Why do we care about this time interval?  That means that any safety function equipment operated past that point in time will not achieve the designed risk reduction factor. The IEC 61511 standard states that our maintenance procedures must require that all equipment be replaced before the end of its useful life rating.  OK, there is a good reason for this.

Then we ask the maintenance supervisor to sign the purchase requisition for the new device.  First response is a…

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